Integrated circuit devices are constructed from a wafer through a process that comprises a number of deposition, masking, diffusion, etching, and implanting steps. Usually, many individual devices are constructed on the same wafer. When the devices are separated into individual rectangular units, each takes the form of an integrated circuit die. In order to interface a die with other circuitry, it is common to mount it in a package with several interconnect. Each die has connections that are then individually connected in to the package interconnect to connect the die to a next level system such as a printed circuit board. The assemblies are then packaged by individually encapsulating them in molded plastic or ceramic covers.
Across virtually all applications, there continues to be growing demand for reducing size and increasing performance of integrated circuits. The seemingly endless restrictions and requirements are no more visible than with products in our daily lives. Smaller and denser integrated circuits are required in many portable electronic products, such as cell phones, portable computers, voice recorders, etc. as well as in many larger electronic systems, such as cars, planes, industrial control systems, etc. As the demand grows for smaller electronic products with more features, manufacturers are seeking ways to include more features as well as reduce the size of the integrated circuit packages. To meet these needs, packaging technologies are increasingly using smaller form factors with more circuits.
Wafer manufacturers strive to reduce transistor or capacitor feature size in order to increase circuit density and enhance functionality. Device geometries with sub-micron line widths are so common that individual chips routinely contain millions of electronic devices. Reduced feature size has been quite successful in improving electronic systems, and continuous development is expected in the future. However, significant obstacles to further reduction in feature size are being encountered. These obstacles include defect density control, optical system resolution limits, and availability of processing material and equipment. Attention has therefore increasingly shifted to integrated circuit packaging as a means to fulfill the relentless demands for enhanced system performance.
To condense further the packaging of individual devices, multi-chip packages have been developed in which more than one device, such as an integrated circuit die, can be included in the same package. Of importance to such complicated packaging designs are considerations of input/output lead count, heat dissipation, matching of thermal expansion and contraction between a motherboard and its attached components, costs of manufacturing, ease of integration into an automated manufacturing facility, package reliability, and easy adaptability of the package to additional packaging interfaces such as a printed circuit board.
Drawbacks of conventional designs include a relatively large footprint of the package on the mounting surface of motherboard. The footprint typically reflects the maximum planar dimension of the package, namely, the x-y dimension of the package. In applications where mounting space is at a premium, such as pagers, portable telephones, and personal computers, among others, a large footprint is undesirable at best. With the goal of increasing the amount of circuitry in a package without increasing the area of the package, so that the package does not take up any more space on the circuit board, manufacturers have been stacking two or more die within a single package. Unfortunately, stacking flipchip integrated circuits requires inefficient wirebonding or redistribution layer interfaces.
Thus, a need still remains for an integrated circuit package system to provide improved function, area, volume, and manufacturing yield. In view of the increasing demand for improved integrated circuits and particularly more functions in smaller products at lower costs, it is increasingly critical that answers be found to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.